Detect circle in binary (thresholded image)

detectcircle

asked 2016-09-24 19:19:58 -0600

greenworld
1 ●1 ●2

Hi everyone, I want to detect circle on the binary image, I try to use HoughCircles but it does not work, could you suggest me some methods to detect circle from binary image.

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When you say "it does not work", could you be more specific? What problems are you having? And could you post an example image?

AJW ( 2016-09-25 03:06:36 -0600 )edit

you need a grayscale, not a binary image.

berak ( 2016-09-27 07:47:49 -0600 )edit

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answered 2016-09-25 03:10:40 -0600

AJW
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One approach might be to use findContours() to get a collection of outline points, then use fitEllipse() to fit an ellipse to them. If the two axis lengths are very similar, it's a circle, otherwise it's not. The ellipse fitting tends to be pretty sensitive to outliers though, so in the case where you do have a circle, you'd need to have very few outline points that don't lie on the circle. It's hard to say without knowing what your data looks like.